In Bannam-myeon, Naju, more than forty burial mounds are scattered around a low peak called Mt. Jamisan, roughly 100 meters in elevation. They're grouped into three clusters: the Deoksan-ri tombs on the eastern ridge, the Sinchon-ri tombs to the northeast, and the Daean-ri tombs along the western ridge. What sets these tombs apart is their burial method. Unlike Goguryeo's stone-mound tombs or Baekje's stone-chamber tombs, these graves used large ceramic jars as coffins. Jar burial was originally common across East Asia as a burial method for commoners — what's unusual here is that it was elevated into the burial practice of the highest tier of local power.
That claim is backed up by what archaeologists actually found inside: gilt-bronze crowns, gilt-bronze shoes, and ring-pommel swords engraved with phoenix motifs — the kind of objects only a king or someone of comparable rank could have owned. This strongly suggests that before the region was fully absorbed into Baekje, an independent Mahan statelet held power here. Exactly who these tomb occupants were, and precisely how their polity related to Baekje, remains a genuinely debated question among scholars. The Daean-ri, Sinchon-ri, and Deoksan-ri tomb clusters were each individually designated as historic sites before being consolidated, in recognition of their shared historical significance, into the single designated site now known as the Naju Bannam Tumuli.